Union Pacific Streamlined Steam Locomotives

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This page was last updated on April 19, 2014.

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(The following comes from research by Gordon McCulloh)


In 1937 Union Pacific applied streamlining to two steam locomotives, UP 2906, a 4-6-2 built in 1920, and UP 7002, a 4-8-2 built in 1922. Both locomotives had received roller bearings in 1936, along with other modernization features to reduce their overall weight and to increase their speed, with the intent to use them as "protection" for the diesel Streamliners.

After roller bearings were applied, and then streamlining the next year, both locomotives were usually assigned to The Forty-Niner train. The two streamlined locomotives were also regularly used on Union Pacific's other important passenger trains, including the summer-only National Parks Special.

The streamlining on both UP 2906 and UP 7002 was removed in 1942 after the Forty-Niner train stopped running in 1941.

Roller Bearings

Letter from C. R. Gray, dated June 28, 1936

Memorandum from President:

The installation of air conditioning equipment on passenger cars during the past few years has increased the trailing load on our passenger locomotives on account of the additional weight and added power required for driving this apparatus.

Schedules have also been shortened, requiring higher speeds and resulting in more exacting demands on locomotive performance.

Investigation indicates that by installing roller bearings on passenger engines, tractive power can be increased and smoother and more efficient operation provided.

In order that thorough test may be made of engines so equipped, it is proposed to equip one Mountain type and one Heavy Pacific type locomotive with roller bearings at estimated capital expenditure of $30,786, for which Union Pacific R.R. Company Request No. 88 (AFE 88 of 1936) is submitted herewith to cover.

This will also provide locomotives capable of high speed operation to meet emergency requirements for streamline trains when necessary.


C. R. Gray


The application of roller bearings and other improvements on UP 2906 were completed by mid March 1937. Funds to apply streamlining were requested on March 17, 1937, and the AFE for UP 2906 was issued on March 26, 1937, and for UP 7002 on April 16, 1937.

The following comes from William Kratville's "Motive Power of the Union Pacific", published in 1960:

[page 119] In 1936, the 2906, which alone was the heaviest of the system's Pacifics, was shopped at Omaha and outfitted with lightweight vanadium steel side and main rods by Timken, needle-bearing valve gear, and roller-bearing lead, trailing and tender trucks. The headlamp was lowered on this locomotive when streamlined. Tests on the lightweight rods and needle bearings on the 2906, along with tests on the similarly equipped 7002, led to the 800 series style rods and bearings in 1937.

(Vanadium Steel -- In 1905, Henry Ford discovered a French-made steel-vanadium alloy. Impressed by its low weight and high strength, he used V-steel in the chassis of the Model-T, reducing the car's overall weight to about half that of contemporary automobiles.)

The 2906, built by Baldwin in 1920, will probably always be remembered mainly though, for its Forty-Niner streamlining in 1937·1942. This engine was selected due to its good performance and rod tests, to be streamlined for the short-lived steam Streamliner between Omaha and Cheyenne. It had a Duplex D-1 stoker, which was applied in 1936.

[page 159] In early 1937, the 7002 was equipped at the Omaha Shops with Timken lightweight rods and needle-bearing valve gear similar to the earlier installation on the 2906.

[page 174] The 2906, a Baldwin built Pacific of 1920 vintage equipped in 1936 with roller bearings and Timken lightweight rods, and the 7002, a fat-boilered Alco Mountain type of 1922, also rebuilt with roller bearings and lightweight rods, were chosen for the speedy task. The Pacific took the train from Omaha to Cheyenne and the Mountain hurried it on west to Ogden. The schedule called for near Streamliner speeds, thus giving the locomotives a good test with their new bearings and rods.

The design for the streamlined shrouds was dreamed up in the Omaha Headquarters and the shrouds fabricated more by customizing rather than actual blueprints. They were applied to both locomotives in April, 1937, at Omaha Shops. The colors fitted the Streamliner hues of Leaf Brown and Streamliner Yellow with thin red striping at the base of the dome casing and on the driver and trailing truck tires. Mr. Owens drew The design.

The streamlined steamers had a UP-designed smoke duct system which drew air in from the front vents but this invention was never considered entirely satisfactory.

Streamlining of the 2906 cost $16,751 to install. Removal costs were $12,732 including many new parts and changing the position of the headlight. Roller-bearings cost $15,452.

The roller-bearings on the 7002 cost $16,308. The streamline shroud cost $25,892.01 to put on, and $22,212 to remove, including the installation of many new parts.

The tender assumed a box-like shroud similar to the New York Central's Mercury, which actually the streamlining resembled. The 2906's tender shroud was extended past the cylindrical tank and the back was flush sheet metal, while the 7002 had an extended vestibule arrangement. Both tenders were equipped during the 1936 shoppings with Timken bearings.

(New York Central's "Mercury" went into service in July 1936 between Detroit and Cleveland. The streamlined styling of the two locomotives, K-5a Pacifics Nos. 4915 and 4917, was done by Henry Dreyfuss.

[page 177] After the shrouding came off in 1942, the 7002's bell was moved above the smokebox front. In the 1946 repainting scheme, the Mountain received two-tone gray with white lettering and chrome cylinder faces. The Pacific was also painted in 1946 in two-tone gray and white lettering, but the cylinder faces were not chromed but treated to locomotive gloss black.

The following comes from "Union Pacific Streamliners" by Ranks and Kratville, published in 1974:

[page 266] Wayne Owens of the Union Pacific Mechanical Dept. drew up the general design for the shrouding, but the artisans at the Omaha Shops fabricated the new contours more by customizing than by actual blueprints. Applied to both locomotives in April 1937, the sheathing was painted leaf brown and Armour yellow with bright red striping on the tires and along the dome castings.

UP 4-6-2 2906

A letter dated March 17, 1937 from President Carl R. Gray states in part:

Engine 2906 was recently turned out of the Omaha shop and has given a remarkable performance.   Mr. Jeffers now wires from Los Angeles advising that in order to have a real test he would like authority to do a rather complete job of streamlining of this engine and tender which will cost about $10,000.

AFE 57 March 26, 1937:

Streamline locomotive U.P. 2906

This locomotive has just been equipped with roller bearings and light weight reciprocating motion work parts. Streamlining is recommended in the further interest of high speed operation as without this improvement a high air resistance is set up at top speeds.

(The streamlining of UP 2906 was completed and the locomotive was substituted several times on the City of Denver Streamliner, and on other high speed trains; see Richard Kindig photo dated June 26, 1937 showing the fully streamlined UP 2906 on Train No. 6 at Cheyenne.)

AFE 57-1 November 2, 1937:

Additional appropriation to cover excess cost of streamlining locomotive UP 2906, being $6,849 over and above the $10,000 allocated (total of $16,849).

UP 4-8-2 7002

AFE 101 April 16, 1937:

Streamline locomotive 7002

This locomotive has just been equipped with roller bearings and light weight reciprocating motion work parts. Streamlining is recommended in the further interest of high speed operation as without this improvement a high air resistance is set up at top speeds.

AFE 101-1   November 2, 1937:

Additional appropriation to cover excess cost of streamlining locomotive 7002, came to $15,178 over and above the $10,850 allocated (total of $26,028).

The Forty-Niner

Operation of The Forty-Niner began in July 1937 in conjunction with the World's Fair in San Francisco. The "Overland Route" railroads (C&NW, UP, SP) began what was to be the last regular transcontinental all-Pullman service with The Forty-Niner. The train was made up of all Pullman owned equipment -- streamlined heavyweights and a lightweight two-car articulated Sleeper set. Both C&NW and the Union Pacific provided streamlined steam locomotives to power the train. Service began out of Chicago on July 8, 1937 and remained in service until July 26, 1941. (Read more about The Forty-Niner passenger train)


Email from Gordon McCulloh dated December 12, 2005, which included photocopies of several internal letters and Authority-For-Expenditure requests and approvals.